In semiconductor manufacturing processes, a process for irradiating a semiconductor wafer with ions which are implanted into the semiconductor wafer is performed in a standard procedure for the purpose of varying conductivity, varying a crystalline structure of the wafer, or the like. An apparatus used in this process is called an ion implantation apparatus. The ion implantation apparatus has a function of accelerating ions generated by an ion source so as to form an accelerated ion beam, and a function of irradiating the entire surface of the semiconductor wafer with the ion beam, through beam scanning, wafer scanning, or a combination thereof. In this case, to what extent ions are implanted into a semiconductor wafer is defined by a semiconductor design, and after the semiconductor design is set once, it is difficult to change the semiconductor design.
There are many types of ion implantation apparatuses, used for semiconductor manufacturing processes, transporting ions generated by an ion source to a wafer as an ion beam. As one type thereof, there is an ion implantation apparatus where slow scanning of a wafer and fast scanning of an ion beam are combined. In the slow scanning of a wafer, a direction in which the wafer undergoes mechanical slow scanning (slow movement) is set as a wafer slow scanning direction. On the other hand, in the fast scanning of an ion beam, a direction in which the ion beam undergoes fast scanning in a direction perpendicular to the wafer slow scanning direction is set as a beam scanning direction (or a fast scanning direction). Thereby, a wafer which is mechanically driven so as to be reciprocally moved in the wafer slow scanning direction is irradiated with an ion beam which reciprocally scans in the beam scanning direction. This ion implantation apparatus is also called a hybrid scanning ion implantation apparatus.
In addition, as another type, there is an ion implantation apparatus using two-dimensional mechanical wafer scanning where slow scanning of a wafer and fast scanning of a wafer are combined. In the wafer mechanical slow scanning, a direction in which a wafer undergoes mechanical slow scanning (slow movement) is set as a wafer slow scanning direction. On the other hand, in the wafer mechanical fast scanning, a wafer fast scanning direction in which a wafer undergoes mechanical fast scanning (fast movement faster than slow movement) in a direction perpendicular to the wafer slow scanning direction is set as the same direction as the beam scanning direction of the hybrid scanning ion implantation apparatus. Thereby, a wafer which is driven so as to be reciprocally moved in the wafer slow scanning direction and also reciprocally moved in the wafer fast scanning direction perpendicular to the wafer slow scanning direction is irradiated with an ion beam (a static ion beam). This ion implantation apparatus is called a two-dimensional mechanical wafer scanning ion implantation apparatus.
As described later, certain embodiments of the present invention may be applied to any one of the hybrid scanning ion implantation apparatus and the two-dimensional mechanical wafer scanning ion implantation apparatus.
In the semiconductor manufacturing processes, semiconductor wafer productivity (hereinafter, abbreviated to wafer productivity) is regarded to be important. As described above, an ion implantation amount to be implanted into a semiconductor wafer in a certain semiconductor manufacturing process is defined. Therefore, in order to increase wafer productivity, it is necessary to increase an amount of ions transported to a semiconductor wafer or efficiently implant ions into a semiconductor wafer.
As described later, the present invention relates to high efficiency ion implantation into a semiconductor wafer.
However, if ions are to be implanted into a semiconductor wafer with high efficiency, typically, the same amount of ions are required to be implanted into the entire surface of the semiconductor wafer in order to manufacture semiconductor devices with the same quality (characteristics) in the wafer surface. In other words, it is necessary to secure wafer in-surface uniformity of an ion implantation amount. Therefore, it is necessary to secure wafer in-surface uniformity of an ion implantation amount and improve wafer productivity.
In the hybrid scanning ion implantation apparatus, as described above, an ion beam reciprocally scans in a beam scanning direction, and a semiconductor wafer is mechanically scanned (moved) in a wafer slow scanning direction perpendicular to the beam scanning direction, thereby implanting ions into the semiconductor wafer. Here, if high efficiency ion implantation into a semiconductor wafer is to be considered, as described later in detail, it may be considered that a semiconductor wafer is fixed and an ion beam is relatively moved. This is also the same for the two-dimensional mechanical wafer scanning ion implantation apparatus. In this case, as one method of high efficiency ion implantation into a semiconductor wafer, there may be a technique of controlling a scanning range (irradiation range) of an ion beam so as to be suitable for a shape of the semiconductor wafer.
Here, in the hybrid scanning ion implantation apparatus, as the technique for controlling a scanning range of an ion beam so as to be suitable for a shape of a semiconductor wafer, there has been proposed a technique for performing control such that a scanning range on a holding member exceeding a shape range of a semiconductor wafer is the same (Patent Literature 1). The holding member is used to hold a semiconductor wafer, and is driven so as to be reciprocally moved in a wafer slow scanning direction in a state of holding the semiconductor wafer.
Patent Literature 1: JP-2009-146757